Researchers who exposed the shortcomings of a security system to protect music on the net are being asked to tell no-one about their findings.

This week a group of academics is poised to go public with research which shows music industry efforts to make digital music pirate proof are doomed.

But the music industry is threatening legal action to gag the group and stop their findings being widely distributed.

However, the legal challenge looks set to fail because copies of the academic paper are already widely available on the internet.

Hacking here

In November last year, the Secure Digitial Music Initiative (SDMI) challenged the internet community to try and defeat the technologies it was backing to protect online music.

The SDMI was set up by the music industry to research and develop technologies that could be used to ensure digital music tracks on the web cannot be pirated.

The challenge offered a $10,000 prize to anyone that managed to defeat any of the six technologies the SDMI put up for testing.

Four of the technologies used watermarks to distinguish between pirated and non-pirated pop and the others wrapped the music in a secure digital wrapper. Almost 450 attempts were made to crack open the technologies in the challenge.

In December, the SDMI handed over reward money to two hackers who managed to defeat some of the technologies.

Research effort

A group of scientists led by Dr Edward Felten, from Princeton, entered the first stage of the competition, but withdrew from the later stages because the SDMI insisted that anyone entering it agree never to reveal how they tackled the technologies.

This week the group, which includes lecturers and students from Princeton and Rice Universities and an employee from the Xerox Palo Alto Research Center, was intending to present a paper based around their SDMI challenge work to the Fourth International Information Hiding Workshop in Pittsburgh.

But now SDMI lawyers have stepped in with the threat of legal action to try to stop the group spreading information about the deficiencies of the technologies, some of which are already being used in commercial products.

The SDMI claims that the public release of the information would put industry efforts to combat copyright piracy in jeopardy.

A letter from the SDMI reads: "Any disclosure of information gained from participating in the Public Challenge would be outside the scope of activities permitted by the Agreement and could subject you and your research team to actions under the Digital Millennium Copyright Act."

Gagging law

The DMCA is a widely criticised act passed in 1998 that makes it illegal to discover or exploit weaknesses in technologies. Cyber-liberty organisations like the Electronic Frontier Foundation are now fighting some of the provisions of the DMCA.

The group of academics has already given in once to the threat of legal action by the SDMI, and it is not yet clear whether the presentation to the conference will go ahead.

However, SDMI attempts to stop the information spreading look doomed because the paper has already started circulating on the internet. Many more websites are expected to publish copies of it over the next few days. Dr Felten said he did not know who had leaked the information.

The paper reveals just how easy it was for the group of researchers to defeat the technologies SDMI hopes will protect pop on the web. The researchers cracked one watermarking system using publicly available information on technologies patented by some of the companies SDMI employed to develop them.

The paper concludes: "We believe no public watermark-based scheme intended to thwart copying will succeed."